File: sbuild-auth-pam-conv-tty.h

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/* Copyright © 2005-2007  Roger Leigh <rleigh@debian.org>
 *
 * schroot is free software: you can redistribute it and/or modify it
 * under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * schroot is distributed in the hope that it will be useful, but
 * WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see
 * <http://www.gnu.org/licenses/>.
 *
 *********************************************************************/

#ifndef SBUILD_AUTH_PAM_CONV_TTY_H
#define SBUILD_AUTH_PAM_CONV_TTY_H

#include <sbuild/sbuild-auth-pam-conv.h>
#include <sbuild/sbuild-auth.h>
#include <sbuild/sbuild-custom-error.h>

#include <security/pam_appl.h>
#include <security/pam_misc.h>

namespace sbuild
{
  /**
   * @brief Authentication conversation handler for terminal devices.
   *
   * This class is an implementation of the auth_pam_conv interface,
   * and is used to interact with the user on a terminal (TTY)
   * interface.
   *
   * In order to implement timeouts, this class uses alarm(2).  This
   * has some important implications.  Global state is modified by the
   * object, so only one may be used at once in a single process.  In
   * addition, no other part of the process may set or unset the
   * SIGALRM handlers and the alarm(2) timer during the time PAM
   * authentication is proceeding.
   */
  class auth_pam_conv_tty : public auth_pam_conv
  {
  public:
    /// Error codes.
    enum error_code
      {
	CTTY,            ///< No controlling terminal.
	TIMEOUT,         ///< Timed out.
	TIMEOUT_PENDING, ///< Time is running out...
	TERMIOS,         ///< Failed to get terminal settings.
	CONV_TYPE        ///< Unsupported conversation type.
      };

    /// Exception type.
    typedef custom_error<error_code> error;

  private:
    /**
     * The constructor.
     *
     * @param auth The authentication object this conversation handler
     * will be associated with.
     */
    auth_pam_conv_tty (auth_ptr auth);

  public:
    /// The destructor.
    virtual ~auth_pam_conv_tty ();

    /**
     * Create an auth_pam_conv_tty object.
     *
     * @param auth The authentication object this conversation handler
     * will be associated with.
     * @returns a shared pointer to the created object.
     */
    static ptr
    create (auth_ptr auth);

    virtual auth_ptr
    get_auth ();

    virtual void
    set_auth (auth_ptr auth);

    virtual time_t
    get_warning_timeout ();

    virtual void
    set_warning_timeout (time_t timeout);

    virtual time_t
    get_fatal_timeout ();

    virtual void
    set_fatal_timeout (time_t timeout);

    virtual void
    conversation (auth_pam_conv::message_list& messages);

  private:
    /**
     * @brief Get the time delay before the next SIGALRM signal.
     *
     * If either the warning timeout or the fatal timeout have
     * expired, a message to notify the user is printed to stderr.  If
     * the fatal timeout is reached, an exception is thrown.
     *
     * @returns the delay in seconds, or 0 if no delay is set.
     */
    int get_delay ();

    /**
     * @brief Read user input from standard input.
     *
     * The prompt message is printed to prompt the user for input.  If
     * echo is true, the user input it echoed back to the terminal,
     * but if false, echoing is suppressed using termios(3).
     *
     * If the SIGALRM timer expires while waiting for input, this is
     * handled by re-checking the delay time which will warn the user
     * or cause the input routine to terminate if the fatal timeout
     * has expired.
     *
     * @param message the message to prompt the user for input.
     * @param echo echo user input to screen.
     * @returns a string, which is empty on failure.
     */
    std::string
    read_string (std::string message,
		 bool        echo);

    /// The auth object.
    weak_auth_ptr  auth;
    /// The time to warn at.
    time_t  warning_timeout;
    /// The time to end at.
    time_t  fatal_timeout;
    /// The time the current delay was obtained at.
    time_t  start_time;
  };

}

#endif /* SBUILD_AUTH_PAM_CONV_TTY_H */

/*
 * Local Variables:
 * mode:C++
 * End:
 */